Replace regex-based IP validation with ipaddress module

[Copilot]

Addresses feedback from PR #6 to fix incomplete IPv6 validation that only supported full notation.

Changes

• Replace regex patterns with ipaddress.ip_address() from Python stdlib
• Supports all valid IPv6 formats: compressed notation (::1), mixed notation (::ffff:192.0.2.1), link-local addresses
• Reduces code from 16 lines to 9 lines while improving correctness

Before/After

# Before: regex only matched full IPv6 notation
ipv6_pattern = r'^([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$'
if not (re.match(ipv4_pattern, ip) or re.match(ipv6_pattern, ip)):
    raise ValidationError(f"Invalid IP address format: {ip}")

# After: handles all RFC-compliant formats
try:
    ipaddress.ip_address(ip)
    return ip
except ValueError:
    raise ValidationError(f"Invalid IP address format: {ip}")

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.